Exclusion system for a key telephone system

Abstract

The exclusion system is employed with a central office/private branch exchange (CO/PBX) system and a party line paging and intercom system. A first circuit is coupled to the "A" lead of the party line system and is responsive to a predetermined potential on this "A" lead to couple a tip conductor and a ring conductor of an associated subset of the party line system to the tip and ring conductors of a selected one of the CO/PBX system and the party line system. A second circuit is coupled to the "A" lead of the party line system to manually generate a first exclusion potential for the party line system to exclude subsets not already connected to the party line system. A third circuit is coupled to the "A" lead of the CO/PBX system and is responsive to a given potential on this "A" lead to automatically produce a second exclusion potential on this "A" lead to exclude subsets not already connected to the CO/PBX system.

I claim: 
     
       1. An exclusion system for a central office/private branch exchange (CO/PBX) system and a party line paging and intercom system, said CO/PBX system having an "A" lead, a tip conductor and a ring conductor and said party line system having an "A" lead, a tip conductor and a ring conductor comprising: first means coupled to said "A" lead of said party line system when said party line system is selected and responsive to a predetermined potential on said "A" lead of said party line system to coupled a tip conductor and a ring conductor of an associated subset to said tip and ring conductors of said selected party line system;   wherein said first means is coupled to said `A` lead of said CO/PBX system when said CO/PEX system is selected and is responsive to a predetermined potential on said `A` lead of said CO/PBX system to couple to the tip conductor and the ring conductor of said associated subset to said tip and ring conductors of said selected CO/PBX system;   second means coupled to said "A" lead of said party line system to manually generate a first exclusion potential for said party line system to exclude subsets not already connected to said party line system; and   third means coupled to said "A" lead of said CO/PBX system responsive to a given potential on said "A" lead of said CO/PBX system to automatically produce a second exclusion potential on said "A" lead of said Co/PBX system to exclude subsets not already connected to said CO/PBX system.   
     
     
       2. An exclusion system according to claim 1, further including fourth means coupled to said "A" lead and said tip conductor of said party line system to enable a paging operation.   
     
     
       3. An exclusion system according to claim 2, wherein said a fourth means includes a relay coupled to said "A" lead of said party line system having at least one contact to connect a paging amplifier to said tip conductor of said party line system when said relay is activated by said predetermined potential on said "A" lead of said party line system.     
     
     
       4. An exclusion system according to claim 2, further including fifth means coupled to said "A" lead and said tip conductor of said party line system to produce a tone burst to indicate that exclusion is in effect in said party line system.   
     
     
       5. An exclusion system according to claim 4, wherein said fifth means includes a first relay coupled to said "A" lead of said party line having at least one normally open contact,   a second relay coupled to said normally open contact, said second relay being energized when said normally open contact is closed when said first relay is energized by said first exclusion potential, and   a third relay coupled to said second relay, said third relay being energized in response to said second relay being energized, said third relay having a normally open contact which connects said tip conductor of said party line system to an oscillator to provide said tone burst.     
     
     
       6. An exclusion system according to claim 4, wherein said first means includes an optical coupler coupled to said tip conductor of a selected one of said party line system and said CO/PBX system,   a first transistor,   a relay coupled as a collector load for said first transistor, said relay having a first contact to connect the ring conductor of said associated subset to said ring conductor of a selected one of said party line system and said CO/PBX system when said relay is energized and a second contact to connect the tip conductor of said associated subset to said optical coupled when said relay is energized, and   first logic circuitry connected from said optical coupler to the base of said first transistor,   said optical coupler and said first logic circuitry to latch said relay in an energized condition.     
     
     
       7. An exclusion system according to claim 6, wherein said first logic circuitry includes a plurality of interconnected NOR gates.     
     
     
       8. An exclusion system according to claim 6, wherein said second means includes a second transistor having its collector connected to said "A" lead of said party line system,   second logic circuitry having its output connected to the base of said second transistor,   ground potential, and   a pushbutton to connect said ground potential to at least two inputs of said second logic circuitry to cause said second transistor to place ground potential on said "A" lead of said party line system to provide said first exclusion potential.     
     
     
       9. An exclusion circuit according to claim 8, wherein said second logic circuitry includes a single NOR gate.     
     
     
       10. An exclusion system according to claim 8, wherein said third means includes a Darlington connected transistor pair coupled to said "A" lead of said CO/PBX system and ground potential, and   third logic circuitry coupled to said Darlington connected transistor pair, said pushbutton and said first logic circuitry to control the operation of said Darlington connected transistor pair and to maintain the latch on said relay, conduction of said Darlington connected transistor pair couples said ground potential to said "A" lead of said CO/PBX system as said second exclusion potential.     
     
     
       11. An exclusion system according to claim 10, wherein said third logic circuitry includes a plurality of interconnected NOR gates.     
     
     
       12. An exclusion system according to claim 1, further including fourth means coupled to said "A" lead and said tip conductor of said party line system to produce a tone burst to indicate that exclusion is in effect in said party line system.   
     
     
       13. An exclusion system according to claim 12, wherein said fourth means includes a first relay coupled to said "A" lead of said party line having at least one normally open contact,   a second relay coupled to said normally open contact, said second relay being energized when said normally open contact is closed when said first relay is energized by said first exclusion potential, and   a third relay coupled to said second relay, said third relay being energized in response to said second relay being energized, said third relay having a normally open contact which connects said tip conductor of said party line system to an oscillator to provide said tone burst.     
     
     
       14. An exclusion system according to claim 12, wherein said first means includes an optical coupler coupled to said tip conductor of a selected one of said party line system and said CO/PBX system,   a first transistor,   a relay coupled as a collector load for said first transistor, said relay having a first contact to connect the ring connector of said associated subset to said ring conductor of a selected one of said party line system and said CO/PBX system when said relay is energized and a second contact to connect the tip conductor of said associated subset to said optical coupled when said relay is energized, and   first logic circuitry connected from said optical coupler to the base of said first transistor,   said optical coupler and said first logic circuitry to latch said relay in an energized condition.     
     
     
       15. An exclusion system according to claim 14, wherein said first logic circuitry includes a plurality of interconnected NOR gates.     
     
     
       16. An exclusion system according to claim 14, wherein said second means includes a second transistor having its collector connected to said "A" lead of said party line system,   second logic circuitry having its output connected to the base of said second transistor,   ground potential, and   a pushbutton to connect said ground potential to at least two inputs of said second logic circuitry to cause said second transistor to place ground potential on said "A" lead of said party line system to provide said first exclusion potential.     
     
     
       17. An exclusion system according to claim 16, wherein said second logic circuitry includes a single NOR gate.     
     
     
       18. An exclusion system according to claim 16, wherein said third means includes a Darlington connected transistor pair coupled to said "A" lead of said CO/PBX system and ground potential, and   third logic circuitry coupled to said Darlington connected transistor pair, said pushbutton and said first logic circuitry to control the operation of said Darlington connected transistor pair and to maintain the latch on said relay, conduction of said Darlington connected transistor pair couples said ground potential to said "A" lead of said CO/PBX system as said second exclusion potential.     
     
     
       19. An exclusion system according to claim 18, wherein said third logic circuitry includes a plurality of interconnected NOR gates.     
     
     
       20. An exclusion system according to claim 1, wherein said first means includes an optical coupler coupled to said tip conductor of a selected one of said party line system and said CO/PBX system,   a first transistor,   a relay coupled as a collector load for said first transistor, said relay having a first contact to connect the ring conductor of said associated subset to said ring conductor of a selected one of said party line system and said CO/PBX system when said relay is energized and a second contact to connect the tip conductor of said associated subset to said optical coupler when said relay is energized, and   first logic circuitry connected from said optical coupler to the base of said first transistor,   said optical coupler and said first logic circuitry to latch said relay in an energized condition.     
     
     
       21. An exclusion system according to claim 20, wherein said first logic circuitry includes a plurality of interconnected NOR gates.     
     
     
       22. An exclusion system according to claim 20, wherein said second means includes a second transistor having its collector connected to said "A" lead of said party line system,   second logic circuitry having its output connected to the base of said second transistor,   ground potential, and   a pushbutton to connect said ground potential to at least two inputs of said second logic circuitry to cause said second transistor to place ground potential on said "A" lead of said party line system to provide said first exclusion potential.     
     
     
       23. An exclusion system according to claim 22, wherein said second logic circuitry includes a single NOR gate.     
     
     
       24. An exclusion system according to claim 22, wherein said third means includes a Darlington connected transistor pair coupled to said "A" lead of said CO/PBX system and ground potential, and   third logic circuitry coupled to said Darlington connected transistor pair, said pushbutton and said first logic circuitry to control the operation of said Darlington connected transistor pair and to maintain the latch on said relay, conduction of said Darlington connected transistor pair couples said ground potential to said "A" lead of said CO/PBX system as said second exclusion potential.     
     
     
       25. An exclusion system according to claim 24, wherein said third logic circuitry includes a plurality of interconnected NOR gates.     
     
     
       26. An exclusion system according to claim 1, wherein said second means includes a transistor having its collector connected to said "A" lead of said party line system,   first logic circuitry having its output connected to the base of said transistor,   ground potential, and   a pushbutton to connect said ground potential to at least two inputs of said first logic circuitry to cause said transistor to place ground potential on said "A" lead of said party line system to provide said first exclusion potential.     
     
     
       27. An exclusion system according to claim 26, wherein said first logic circuitry includes a single NOR gate.     
     
     
       28. An exclusion system according to claim 26, wherein said third means includes a Darlington connected transistor pair coupled to said "A" lead of said CO/PBX system and ground potential, and   second logic circuitry coupled to said Darlington connected transistor pair, said pushbutton and said first logic circuitry to control the operation of said Darlington connected transistor pair, conduction of said Darlington connected transistor pair couples said ground potential to said "A" lead of said CO/PBX system as said second exclusion potential.     
     
     
       29. An exclusion system according to claim 28, wherein said second logic circuitry includes a plurality of interconnected NOR gates.     
     
     
       30. An exclusion system according to claim 1, wherein said third means includes a Darlington connected transistor pair coupled to said "A" lead of said CO/PBX system and ground potential, and   logic circuitry coupled to said Darlington connected transistor pair to control the operation of said Darlington connected transistor pair, conduction of said Darlington connected transistor pair couples said ground potential to said "A" lead of said CO/PBX system as said second exclusion potential.     
     
     
       31. An exclusion system according to claim 30, wherein said logic circuitry includes a plurality of interconnected NOR gates.